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Old November 6 2013, 03:24 PM   #9
Metryq
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Re: 1 in 5 stars have earth-like planets around them!

Astronomers refer to "Terrestrials" and "Jovians." Perhaps those are antiquated terms now, I don't know. But I would not call Venus "Earth-like." Mercury is a "Terrestrial," yet much more like the Moon than Earth—or Venus.

As for the "habitable zone" argument, the Earth and Moon are in the same zone, and several theories describe the Moon fissioning off from Earth. So why doesn't it have at least one sixth the atmosphere of Earth and some of Earth's other attributes? If life is ever found on Titan, for example, that would scrap the "habitable zone" argument.

The point is, journalists or astronomers quoted as saying "Earth-like" is imprecise and very misleading... especially when one considers the hair-splitting that went into redefining Pluto—a subject some people feel passionately about. Sloppy language does not lead to sloppy thinking, but it can. In the same fashion, precise language, such as the practice of using "significant figures," even when it is zero, is a hallmark of science.

All these exoplanetary reports should be using terms like "Earth-sized" or "Earth mass," but that doesn't excite the mouth-breathers like "Earth-like." We can pack up the space camper and go right now!
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